Air filter assembly for an engine

ABSTRACT

An engine includes a breather conduit, an intake conduit, and an air filter assembly. The air filter assembly includes a case and a filter element. The case includes a first opening for receiving the breather conduit, and a second opening for receiving the intake conduit. The filter element includes a first aperture, a second aperture, and filter media at least partially defining an interior chamber of the filter element. The first and second apertures of the filter element are at least partially aligned with the first and second openings of the case, respectively. The filter element is positioned in the case such that the breather conduit and the intake conduit are directed to or from the interior chamber of the filter element, such that air filtered by the filter media mixes with unfiltered gases from the breather conduit in the interior chamber of the filter element prior to entering the intake conduit.

BACKGROUND

The present application generally relates to the field of air filtersand air filter assemblies, such as those for use with internalcombustion engines.

An internal combustion engine typically includes an air filter forremoving dust, dirt, or other debris from air entering the engine forcombustion processes. The air filter assembly may be housed in a caseand include a filter element, which includes filter media, such asfilter paper, foam, mesh, oil bath, or other media. After passingthrough the filter media, the filtered air is typically routed to acarburetor to pick up fuel and then to a combustion chamber of theengine. Removing the debris from the air helps to preserve the movingcomponents of the engine, such as the piston and crankshaft, avoidingexcess friction and wear, as well as preventing clogging of the fueldelivery system.

SUMMARY

One embodiment of the invention relates to an engine, which includes abreather conduit, an intake conduit, and an air filter assembly. The airfilter assembly includes a case and a filter element. The case includesa first opening for receiving the breather conduit, and a second openingfor receiving the intake conduit. The filter element includes a firstaperture, a second aperture, and filter media at least partiallydefining an interior chamber of the filter element. The first and secondapertures of the filter element are at least partially aligned with thefirst and second openings of the case, respectively. The filter elementis positioned in the case such that the breather conduit and the intakeconduit are directed to or from the interior chamber of the filterelement, such that air filtered by the filter media mixes withunfiltered gases from the breather conduit in the interior chamber ofthe filter element prior to entering the intake conduit.

Another embodiment of the invention relates to an air filter assemblyfor an internal combustion engine. The air filter assembly includes abase and a cover configured to be fastened to the base. The base andcover define an interior volume of the air filter assembly sized toreceive an air filter element. The air filter assembly further includesa first opening through at least one of the base and the cover, and asecond opening through at least one of the base and the cover. The firstopening is configured to receive air from a crankcase breather conduit,and the second opening is configured to deliver air to an air intakeconduit. The first and second openings are symmetrically arrangedrelative to the interior volume.

Yet another embodiment of the invention relates to a filter element foran air filter assembly of an internal combustion engine. The filterelement includes a top wall, a bottom wall, and filter media extendingbetween the top and bottom walls. The filter element further includes afirst aperture configured to receive air from a breather conduit and asecond aperture configured to deliver air to an intake conduit. Thefirst and second apertures are equally spaced apart from the center ofthe filter element.

Still another embodiment of the invention relates to an engine, whichincludes a breather conduit, an intake conduit, and an air filterassembly. The air filter assembly includes a filter element and a case.The filter element includes a top wall, a bottom wall, a first aperturethrough the bottom wall, a second aperture through the bottom wall, andfilter media extending between the top and bottom walls and at leastpartially defining an interior chamber of the filter element. The firstand second apertures are the same shape, the same size, and are equallyspaced apart from the center of the bottom wall. The case includes abase, a first opening for receiving the breather conduit formed in thebase, a second opening for receiving the intake conduit formed in thebase, and a cover configured to be fastened to the base. The base andthe cover define an interior volume of the air filter assembly sized toreceive the filter element with the first aperture and the secondaperture of the filter element being at least partially aligned with thefirst opening and the second opening of the case, respectively. Thefilter element is configured to be received in the case such that thebreather conduit and the intake conduit are directed to and from theinterior chamber of the filter element, respectively, whereby airfiltered by the filter media mixes with unfiltered gases from thebreather conduit in the interior chamber of the filter element prior toentering the air intake conduit.

Another embodiment of the invention relates to a filter element for anair filter assembly of an engine. The filter element includes filtermedia, a first wall, and a second wall. The filter media has a closedloop, a top, and bottom. The first wall is provided on the top of thefilter media, and has no openings. The second wall is provided on thebottom of the filter media, and has two separate openings.

Another embodiment of the invention relates to a method of manufacturinga filter element for an air filter of an engine. The method includespouring a first amount of foam material into a first mold, inserting afirst portion of filter media into the first amount of foam material,and solidifying the first amount foam material to form a first wall ofthe filter element such that the first portion of the filter media isintegrated with the first wall. The method further includes pouring asecond amount of foam material into a second mold, inserting a secondportion of the filter media into the second amount of foam material, andsolidifying the second amount of foam material to form a second wall ofthe filter element such that the second portion of the filter media isintegrated with the second wall. One of the first and second wallsincludes two separate openings.

Alternative exemplary embodiments relate to other features andcombinations of features as may be generally recited in the claims.

BRIEF DESCRIPTION OF THE FIGURES

The disclosure will become more fully understood from the followingdetailed description, taken in conjunction with the accompanyingfigures, in which:

FIG. 1 is a perspective view of an internal combustion engine accordingto an exemplary embodiment of the invention.

FIG. 2 is a perspective view of a cover of an air filter assemblyaccording to an exemplary embodiment of the invention, in a firstorientation.

FIG. 3 is a perspective view of the cover of FIG. 2 in a secondorientation.

FIG. 4 is a perspective view of a base of an air filter assemblyaccording to an exemplary embodiment of the invention, in a firstorientation.

FIG. 5 is a perspective view of the base of FIG. 4 in a secondorientation.

FIG. 6 is a perspective view of a filter element for an air filterassembly according to an exemplary embodiment of the invention, in afirst orientation.

FIG. 7 is a perspective view of the filter element of FIG. 6 in a secondorientation.

FIG. 8 is a bottom view of the filter element of FIG. 6.

FIG. 9 is a sectional view of the filter element of FIG. 6, taken alongline 9-9 of FIG. 8.

FIG. 10 is a perspective view of the base of FIG. 4 and the filterelement of FIG. 6.

FIG. 11 is a sectional view of the base of FIG. 10, taken along line11-11 of FIG. 10.

DETAILED DESCRIPTION

Before turning to the figures, which illustrate the exemplaryembodiments in detail, it should be understood that the presentapplication is not limited to the details or methodology set forth inthe description or illustrated in the figures. It should also beunderstood that the terminology is for the purpose of description onlyand should not be regarded as limiting.

Referring to FIG. 1, an engine is shown as an internal combustion engine110, which includes an engine cover 112, a crankcase 114, a fuel tank116 and cap 118, and a muffler 120. In some embodiments, the engine 110includes an automatic rewind 122 for a recoil starter system, and ahandle 124 for an associated pull cord. In some embodiments, the engine110 further includes a rocker cover 126. According to an exemplaryembodiment, the engine 110 includes an air filter assembly 128, whichincludes a case 130 with a cover 132. A primer bulb assembly 134 may beintegrated with the case 130 of the air filter assembly 128. In otherembodiments, the primary bulb or primary bulb assembly is not included.

According to an exemplary embodiment, the air filter assembly 128 iscoupled to a breather conduit 136 and an intake conduit 138 of theengine 110. The breather conduit 136 may include a rubber hose, metalpipe, or another form of conduit that is coupled to the crankcase 114 ofthe engine 110, and is configured to relieve fluctuating pressureswithin the crankcase 114 due to movement of the piston, changes intemperature expanding or contracting gases in the crankcase 114, orother reasons. The intake conduit 138 is configured to provide filteredair from the air filter assembly 128 to the combustion chamber of theengine 110. In some embodiments, the intake conduit 138 is coupled to acarburetor (not shown), such as by way of an intake manifold, an intakepassage, or directly to the throat of the carburetor. In otherembodiments, the intake conduit 138 is coupled to a fuel injector oranother system of the engine 110. The intake conduit 138 may be separateor may be at least partially integrated with the engine block orcylinder head (not shown), and may be formed from metal, plastic, orother materials.

In some embodiments, the engine 110 is a vertically-shafted engine, asshown in FIG. 1 in a generally upright position. In other contemplatedembodiments, the engine may be horizontally-shafted, where the shaftwould extend from a side of the engine, such as in a location generallyproximate to the locations of the primer bulb 134 or rocker cover 126shown in FIG. 1. Although shown in FIG. 1 as an overhead-valve enginewith the rocker cover 126, in other embodiments the engine 110 may be anL-head engine or another configuration of engine. In contemplatedembodiments, the engine 110 may have one, two, or more cylinders. Theengine 110 may run on a four-stroke cycle or a two-stroke cycle. Incontemplated embodiments, the engine 110 may be gasoline-powered,diesel, or otherwise fueled. In some contemplated embodiments, theengine 110 may be configured to drive a lawn mower, a portable electricgenerator, pressure washer, snow thrower, chipper/shredder, logsplitter, tractor, riding mower, or other outdoor power equipment. Inother contemplated embodiments, the air filter assembly 128 may be usedto filter air that is not provided to an internal combustion engine,such as filtered air for a pneumatic pump or actuator, a cooling system,or another system.

Referring to FIGS. 2-5, the cover 132 (FIGS. 2-3) of the air filterassembly 128 is designed to fasten and unfasten to a base 140 (FIGS.4-5) of the air filter assembly 128, to form the case 130 (FIG. 1). Theexterior 142 (FIG. 2) of the cover 132 provides an outside surface ofthe engine 110, and the exterior 144 (FIG. 5) of the base 140 isconfigured to be coupled to the engine 110, such as fastened via boltholes 196 (FIGS. 4-5) or other fasteners. The interior 146 (FIG. 3) ofthe cover 132 and the interior 148 (FIG. 4) of the base 140 at leastpartially form an interior volume of the air filter assembly 128. Insome embodiments, the cover 132 and base 140 are molded from a plasticmaterial. In other embodiments, at least one of the cover 132 and base140 is stamped or assembled from aluminum, another material, or isformed from a combination of materials and manufacturing processes.

According to an exemplary embodiment, the cover 132 further includeshinge wings 150, an integral hook 152, and a guide structure 154 (e.g.,flange) (FIGS. 2-3). The hinge wings 150 are designed to couple withpins 156 (FIGS. 4-5) integrally formed with the base 140. The cover 132is then configured to rotate about the pins 156. In some embodiments,hinge wings are integrally formed with the base 140 and the pins areintegrally formed with the cover 132. In other embodiments, the cover132 is fastened to the base 140 with other forms of integral or separatefasteners (e.g., nuts and bolts).

According to an exemplary embodiment, the hook 152 is configured to snapor otherwise fasten to a corresponding catch 158 on the base 140 (FIGS.4-5) for securing the case 130 in a closed configuration. Guides 194facilitate placement of the hook 152 and help to prevent lateralslipping of the hook 152 from the catch 158. To release the hook 152,the top of the hook 152 may be lifted off the catch 158. The cover 132may then be rotated about the pins 156 to an open configuration. Inother contemplated embodiments, other forms of releasable lockingmechanisms are used, such as sliding latches, screws, etc. Opening thecover 132 allows for insertion, removal, and checking of the status of afilter element (see, e.g., filter element 160 as shown in FIGS. 6-10)positioned within the interior volume 146, 148 of the case 130.

Referring now to FIGS. 6-9, a filter element 160 includes a top wall162, a bottom wall 164, and filter media 166 extending between the topand bottom walls 162, 164. According to an exemplary embodiment thefilter media 166 at least partially defines an interior chamber 168 ofthe filter element 160, with the top and bottom walls 162, 164 also atleast partially defining the interior chamber 168. In some suchembodiments, the filter media 166 is structured such that the filtermedia 166 has a closed-loop, such as the periphery of a circle, ellipse,rectangle, or other closed-loop shape. In some contemplated embodiments,the filter media 166 may fill some or all of the space between the topand bottom walls 162, 164. In other contemplated embodiments, a filterelement includes a bottom wall and filter media, without a top wallother than the top of the filter media. In some embodiments, the filterelement 160 has a periphery formed from straight segments extendingbetween rounded ends.

According to an exemplary embodiment, the top and bottom walls 162, 164are formed from a rigid material, such as plastic, cardboard, wood,composite, aluminum, or other materials. In some embodiments, the filtermedia 166 includes pleated filter paper, while in other embodiment otherforms of filter media are used. In some embodiments, the filter element160 is generally oblong in shape, with straight sides and rounded ends.However, in contemplated embodiments, the filter element may berectangular, elliptical, asymmetrically-shaped, or otherwise shaped.

Referring to FIGS. 7-8, the filter element 160 includes a first aperture170 (e.g., opening, hole) configured to receive air from the breatherconduit 136 (FIG. 1), and a second aperture 172 configured to provideair to the intake conduit 138 (FIG. 1). According to some exemplaryembodiments, the apertures 170, 172 are substantially the same size andshape, allowing for minor variations in some such embodiments. In othercontemplated embodiments, one aperture may be substantially larger orsmaller than the other aperture, such as by a factor of two, five, orten times. In some embodiments the apertures 170, 172 are circular,while in other contemplated embodiments, the apertures may be hexagonal,oblong, or otherwise shaped. While portions of the apertures 170, 172are substantially the same size, in some embodiments, the cross-sectionsof the apertures 170, 172 may differ from one another in other portionsof the apertures 170, 172, along the paths of the apertures 170, 172through the bottom wall 164 of the filter element 160. Similarly, whilethe openings 180, 182 may include nearly identical portions, the opening180 shown in FIGS. 4 and 11 includes a step 198 (e.g., shoulder)changing the cross-sectional width of a portion of the opening 180.

During use, the portion of the filter media 166 that is closer to thesecond aperture 172, which may be associated with (e.g., directlycoupled to, connected to) the intake conduit 138, may collect moredebris than the portion of the filter media 166 that is closer to thefirst aperture 170, which may be associated with the breather conduit136. According to an exemplary embodiment, the apertures 170, 172 arearranged on the filter element 160 in a manner configured to allow forreversal of the filter element 160 so that the first aperture 170 isinstead associated with the intake conduit 138, and the second aperture172 is associated with the breather conduit 136 in the air filterassembly 128. Accordingly, in some such embodiments, the sizing andspacing of the first and second apertures 172, 170 allows the filterelement 160 to be rotated, with the cleaner portion of the filter media166 moved closer to the intake conduit 138, which is intended to allowfor a longer life of the filter element 160 by more evenly using thefilter media 166. However, in other embodiments, the filter is notreversible.

According to an exemplary embodiment, use of two, evenly-sized andcommonly-shaped apertures 170, 172 defined in the structure of thefilter element 160 facilitates reversing of the filter element 160. Insome embodiments, the apertures 170, 172 are symmetrically arranged onthe same wall 162, 164 of the filter element 160, where rotating thefilter element 160 by 180-degrees switches the apertures 172, 170 (seeFIGS. 7-8). The section line 9-9 of FIG. 8 also defines a line ofsymmetry with respect to the apertures 170, 172. A line orthogonal tothe section line 9-9, along the exterior of the bottom wall 164 andpassing through the center of the base 140 symmetrically divides eachaperture individually in some embodiments. In other embodiments,apertures 170, 172 may be positioned on different walls 162, 164, eitheraligned or oppositely positioned on the different walls 162, 164 suchthat flipping the filter element 160 switches the apertures 170, 172. Instill other contemplated embodiments, the filter element may not bereversible.

According to an exemplary embodiment, the aperture of the filter element160 that is associated with the intake conduit 138 is not centeredwithin the filter element 160. Instead each aperture 172, 170 iseccentrically positioned, and the interior chamber 168 within the filtermedia 166 is elongated, allowing for a large volume for fresh air thathas been filtered and air from the breather conduit 136 to mix beforeentering the intake conduit 138. Mixing of fresh air and breather airmay reduce hydrocarbon emissions by better facilitating the burning ofhydrocarbons carried in the breather air. Additionally, increasing thesurface area of the filter media 166 surrounding the interior chamber168, such as may be accomplished with an elongated shape of the filterelement 160, is intended to widen the flow path of air through thefilter media 166, increasing the life of the filter element 160 anddecreasing drag upon the intake of air into the engine 110.

Referring again to FIGS. 3-4, the base 140 of the air filter assembly128 includes an area 174 for receiving the filter element 160, oranother compatible filter element. Within the area 174 for receiving thefilter element 160, the base 140 includes a first boss 176 (e.g.,extension, protrusion, guide) and a second boss 178. According to anexemplary embodiment, the bosses 176, 178 are sized and positioned toreceive the first and second apertures 170, 172 of the filter element160. In some embodiments, the apertures 170, 172 each include a beveledopening designed to facilitate receipt of the bosses 176, 178. In someembodiments, the bosses 176, 178 each include a tapered end designed tofacilitate insertion into the apertures 170, 172. For example, theapertures 170, 172 in FIG. 7 are shown to include rounded outer edges,and the bosses 176, 178 in FIG. 4 are shown to narrow toward the topedge.

According to an exemplary embodiment, a first opening 180 is defined inthe first boss 176, and a second opening 182 is defined in the secondboss 178. In some embodiments, the first opening 180 and the secondopening 182 are substantially the same size and shape as one another,and are formed by the interior of the bosses 176, 178. Further, theopenings 180, 182 are substantially equally spaced apart from the centerof the area 174 for receiving the filter element 160 in the base 140.The spacing and location are intended to improve mixing of the fresh airand breather air prior to combustion, to reduce hydrocarbon emissions.In other contemplated embodiments one or more of the bosses 176, 178,and one or more of the openings 180, 182 may be formed in a cover of acase of an air filter assembly. In other contemplated embodiments, morethan two bosses and openings are formed in a case and more than twoapertures are formed in the respective filter element, such as withembodiments where two or more breather conduits are used.

Referring now to FIGS. 4, 7, and 10, when the filter element 160 isinserted into the area 174 of the base 140 for receiving the filterelement 160, the bosses 176, 178 are inserted into the apertures 170,172, and a protrusion 184 (e.g., seal) of the base 140 is received in agroove 186 on the filter element 160. Clips 188 formed in the base 140engage the bottom wall 164 of the filter element 160, and may serve tofacilitate attachment the air cleaner base 140 to the engine. In somecontemplated embodiments, the clips 188 may include a hook, flange, orother form of connector attached to a flexible portion of material,where the hook is biased to catch a corresponding portion of the filterelement 160, such as the bottom wall 162. The clips 188 may lock ontothe bottom wall 162 as the filter element 160 is placed in the area 174.The clips 188 may also release when pulled backward, away from thefilter element 160, to allow for removal of the filter element 160. Inother contemplated embodiments, the clips 188 may operate by insertingthrough corresponding holes in a filter element, by rotating over aportion of the filter element to latch onto the filter element, or mayotherwise operate to hold the filter element in place. In still otherembodiments, no clips are included. On the exterior 144 of the base 140,the first opening 180 narrows to a connector 190 configured to receivethe breather conduit 136, and the second opening is sized and configuredto couple with the intake conduit 138. A hose tail connector 192 extendsfrom a conduit behind the primer bulb 134.

According to an exemplary embodiment, the walls 162, 164 on the top andbottom of the filter element 160 are designed to easily slide over thebosses 176, 178, facilitating quick insertion and removal of the filterelement 160 from the air filter case 130 because the apertures 170, 172are fixedly positioned to fit over the associated openings 180, 182 inthe case 130. In some such embodiments, there is no flexing or bendingof the filter media 166 during insertion, or accidental catching ortearing of filter media 166 upon removal due to the design of the walls162, 164 and receiving area 174. Furthermore, the interface betweensolid surfaces of the bosses 176, 178 and solid surfaces of theapertures 170, 172 in the bottom wall 162 may allow for a tighter sealbetween the filter element 160 and the breather and intake conduits 136,138. According to such an embodiment, there is a greatly reducedlikelihood of an air leak around the filter media 166, such as mayotherwise occur if a filter media had been improperly installed in thecorresponding air filter.

During operation, as the engine 110 is running, fresh air (e.g., outsideair) is drawn into the interior volume 146, 148 of the air filterassembly 128 through openings in the cover 132. Debris is filtered outof the fresh air as the fresh air passes through the filter media 166.Concurrently, pressure fluctuations in the crankcase of the engine 110draw or provide air through the first aperture 170 by way of thebreather conduit 136, which may contain oil from the crankcase. Thebreather air and the fresh air are provided in the interior chamber 168of the filter element 160. The air is then drawn through the secondaperture 172 and to the interior of the engine 110 by way of the intakeconduit 138 for combustion within the engine 110. In some embodiments,the aperture 170 associated with the breather conduit 136 is positionedvertically above the aperture 172 associated with the intake conduit 138so that gravity pulls any liquids transferred from the breather conduit136 down into the intake conduit 138 for combustion.

In some embodiments, the walls 162, 164 of the filter element 160 areformed from a foam material, such as flexible urethane foam. In somesuch embodiments, a first amount of the foam material in a fluid form ispoured into a mold configured to form one of the walls 162, 164. A topor bottom edge of pleated paper 166 (or other filter media) is insertedinto the foam material prior to solidification of the foam material inthe mold. As the foam material solidifies, the edge of the pleated paperis then integrated with (e.g., fixed to, adhered to) the first wall. Asecond amount of foam material is poured into another mold configured toform the other of the walls 162, 164. The free edge of the pleated paperis then inserted into the second amount of foam material, prior tosolidification of the second wall. According to an exemplary embodiment,no fasteners are used to form the filter element 160, other than thepleated paper 166 and foam material.

In some embodiments, pleating of the paper 166 provides rigidity to thefilter element 160 between the walls 162, 164, holding the walls 162,164 apart and in place relative to one another. Additionally, thepleating increases the surface area of the paper 166, increasing thearea through which air may be filtered. Use of solidified (e.g.,hardened, rubbery) foam material for the walls 162, 164 is intended toimprove the seal between the apertures 170, 172 of the filter element160 and the bosses 176, 178, because the apertures 170, 172 may stretcharound and hold tightly to the outer walls of the bosses 176, 178. Inother contemplated embodiments, only the bottom wall 164 is formed fromfoam material.

The construction and arrangements of the air filter assembly, as shownin the various exemplary embodiments, are illustrative only. Althoughonly a few embodiments have been described in detail in this disclosure,many modifications are possible (e.g., variations in sizes, dimensions,structures, shapes and proportions of the various elements, values ofparameters, mounting arrangements, use of materials, colors,orientations, etc.) without materially departing from the novelteachings and advantages of the subject matter described herein. Someelements shown as integrally formed may be constructed of multiple partsor elements, the position of elements may be reversed or otherwisevaried, and the nature or number of discrete elements or positions maybe altered or varied. The order or sequence of any process, logicalalgorithm, or method steps may be varied or re-sequenced according toalternative embodiments. Other substitutions, modifications, changes andomissions may also be made in the design, operating conditions andarrangement of the various exemplary embodiments without departing fromthe scope of the present invention.

What is claimed is:
 1. An engine, comprising: a breather conduit; anintake conduit; an air filter assembly comprising: a case comprising afirst opening for receiving the breather conduit, and a second openingfor receiving the intake conduit, and a filter element comprising afirst aperture, a second aperture, and filter media at least partiallydefining an interior chamber of the filter element; wherein the firstand second apertures of the filter element are at least partiallyaligned with the first and second openings of the case, respectively;wherein the filter element is positioned in the case such that thebreather conduit and the intake conduit are directed to or from theinterior chamber of the filter element, whereby air filtered by thefilter media mixes with unfiltered gases from the breather conduit inthe interior chamber of the filter element prior to entering the intakeconduit.
 2. The engine of claim 1, wherein the filter element comprisesa top wall, a bottom wall, and the filter media extending between thetop and bottom walls.
 3. The engine of claim 1, wherein the firstopening is positioned above the second opening when the engine is in anupright orientation.
 4. An air filter assembly for an internalcombustion engine, comprising: a base; a cover configured to be fastenedto the base, wherein the base and the cover define an interior volume ofthe air filter assembly; a first opening through at least one of thebase and the cover, the first opening configured to receive air from acrankcase breather conduit; a second opening through at least one of thebase and the cover, the second opening configured to deliver air to anintake conduit; an air filter element positioned within the interiorvolume, wherein the air filter element comprises first and secondapertures configured to be at least partially aligned with the first andsecond openings, wherein the air filter element comprises a filter mediaat least partially defining an interior chamber of the air filterelement, and wherein the first and second apertures open to the interiorchamber; a first boss for receiving the first aperture of the air filterelement, wherein the first opening is formed in the first boss; and asecond boss for receiving the second aperture of the air filter element,wherein the second opening is formed in the second boss, wherein thefirst and second openings are symmetrically arranged relative to theinterior volume, wherein the first and second openings are substantiallythe same size as one another, wherein the first and second bosses aresubstantially the same shape as one another, and wherein the first andsecond openings are defined in the base.
 5. The air filter assembly ofclaim 4, wherein the first and second bosses are integrally formed inthe base.
 6. An engine, comprising: a breather conduit; an intakeconduit; an air filter assembly comprising: a filter element comprisinga top wall, a bottom wall, a first aperture through the bottom wall, asecond aperture through the bottom wall, and filter media extendingbetween the top and bottom walls and at least partially defining aninterior chamber of the filter element, wherein the first and secondapertures are the same shape, the same size, and are equally spacedapart from a center of the bottom wall; a case comprising a base, afirst opening for receiving the breather conduit formed in the base, asecond opening for receiving the intake conduit formed in the base, anda cover configured to be fastened to the base, wherein the base and thecover define an interior volume of the air filter assembly sized toreceive the filter element with the first aperture and the secondaperture of the filter element being at least partially aligned with thefirst opening and the second opening of the case, respectively; whereinthe filter element is configured to be received in the case such thatthe breather conduit and the intake conduit are directed to and from theinterior chamber of the filter element, respectively, whereby airfiltered by the filter media mixes with unfiltered gases from thebreather conduit in the interior chamber of the filter element prior toentering the intake conduit.
 7. The engine of claim 6, wherein the firstand second apertures of the filter element are symmetrically arrangedwith respect to one another about a first line bisecting the bottom wallof the filter element, and are symmetrically arranged with respect tothemselves about a second line bisecting the bottom wall.
 8. The engineof claim 7, wherein the filter element is fully operational whenoriented such that the first and second apertures of the filter elementare at least partially aligned with the second and first openings of thecase, respectively, whereby if one side of the filter media clogs fasterthan another, flipping the filter element increases the usable life ofthe filter media.
 9. The engine of claim 8, further comprising: a firstboss for receiving the first aperture of the filter element, wherein thefirst opening is formed in the first boss; and a second boss forreceiving the second aperture of the filter element, wherein the secondopening is formed in the second boss.
 10. The engine of claim 9, whereinthe first opening is positioned above the second opening when the engineis in an upright orientation, whereby gravity draws liquid emanatingfrom the breather conduit toward the intake conduit.